Canada has traditionally been a much stronger Rugby Union playing country than USA.
We all know Union numbers are pretty dodgy, but they claim to have nearly 30k senior players and about 50k junior players in Canada, and have a tradition going back to the 1860s.
Canadian football is also different to American gridiron, and is seen to be more like the original Rugby roots (although I've never seen a game and don't know if that means skills are more transferable).
In short, it will be much easier to develop players in Canada than in many countries because they have a base to work on.
In America we have seen many guys raised on gridiron make a reasonably successful transition to Rugby League, with many examples of guys playing in semi pro comps in Australia and England.
If the Wolfpack make the effort to develop Canadian players from Union and Canadian football, they should be able to develop a few players of ESL standard within a reasonable time frame.